OVERVIEW

#This exercise accompanies the lessons in Environmental Data Analytics on Data Exploration.

Directions

  1. Rename this file <FirstLast>_A03_DataExploration.Rmd (replacing <FirstLast> with your first and last name).
  2. Change “Student Name” on line 3 (above) with your name.
  3. Work through the steps, creating code and output that fulfill each instruction.
  4. Be sure to answer the questions in this assignment document.
  5. When you have completed the assignment, Knit the text and code into a single PDF file.
  6. After Knitting, submit the completed exercise (PDF file) to the dropbox in Sakai.

The completed exercise is due on Sept 30th.

Set up your R session

  1. Check your working directory, load necessary packages (tidyverse), and upload two datasets: the ECOTOX neonicotinoid dataset (ECOTOX_Neonicotinoids_Insects_raw.csv) and the Niwot Ridge NEON dataset for litter and woody debris (NEON_NIWO_Litter_massdata_2018-08_raw.csv). Name these datasets “Neonics” and “Litter”, respectively. Be sure to include the subcommand to read strings in as factors.
#setwd("/home/guest/R/EDA-Fall2022) 
#change wd from assingments to main eda folder

#install.packages("tinytex")
#tinytex::install_tinytex()

#Allow for code and comments to not run off page when knitting file. Note- add to top of every rmd

#install.packages('formatR')
knitr::opts_chunk$set(tidy.opts=list(width.cutoff=80), tidy=TRUE)


#installing necessary packages, one installed add # to knit assignment 
#install.packages("tidyverse")
#install.packages("dplyr")
library(ggplot2)
#install.packages("lubridate")
library(lubridate)
#adding datasets needed for assingment

Neonics.data <-read.csv("Data/Raw/ECOTOX_Neonicotinoids_Insects_raw.csv", stringsAsFactors = TRUE)
Litter.data <-read.csv("Data/Raw/NEON_NIWO_Litter_massdata_2018-08_raw.csv", stringsAsFactors = TRUE)

#str(Neonics.data$Effect)

#Explore dataset
#View(Neonics.data) 
#class(Neonics.data) #data.frame

Learn about your system

  1. The neonicotinoid dataset was collected from the Environmental Protection Agency’s ECOTOX Knowledgebase, a database for ecotoxicology research. Neonicotinoids are a class of insecticides used widely in agriculture. The dataset that has been pulled includes all studies published on insects. Why might we be interested in the ecotoxicology of neonicotinoids on insects? Feel free to do a brief internet search if you feel you need more background information.

Answer: This database provides information on adverse effects of single chemical stressors aquadic and terrestiral species. Inspect are important for polluation and food production and understanding stressors are important.

  1. The Niwot Ridge litter and woody debris dataset was collected from the National Ecological Observatory Network, which collectively includes 81 aquatic and terrestrial sites across 20 ecoclimatic domains. 32 of these sites sample forest litter and woody debris, and we will focus on the Niwot Ridge long-term ecological research (LTER) station in Colorado. Why might we be interested in studying litter and woody debris that falls to the ground in forests? Feel free to do a brief internet search if you feel you need more background information.

Answer: Understanding forest litter and woody debris helps us better understand the health of our mountains. This monitoirng allows us to understand diverse ecosystems in multiplal spatial and temporral scales. It also helps better understand the biodiversity in our ecosystem. Litter and woody debris sampling help provides understanding about plans.

  1. How is litter and woody debris sampled as part of the NEON network? Read the NEON_Litterfall_UserGuide.pdf document to learn more. List three pieces of salient information about the sampling methods here:

Answer: 1.Litter and fine woody debris are collected from elevated ground traps 2. Sampling desing ecompases spaital paramaters such as NEON sites with woody vegitation >2M. 3. Ground traps are sampled once per year and more frequenly depending on density of vegitation and forest.

Obtain basic summaries of your data (Neonics)

  1. What are the dimensions of the dataset?
colnames(Neonics.data)
##  [1] "CAS.Number"                       "Chemical.Name"                   
##  [3] "Chemical.Grade"                   "Chemical.Analysis.Method"        
##  [5] "Chemical.Purity"                  "Species.Scientific.Name"         
##  [7] "Species.Common.Name"              "Species.Group"                   
##  [9] "Organism.Lifestage"               "Organism.Age"                    
## [11] "Organism.Age.Units"               "Exposure.Type"                   
## [13] "Media.Type"                       "Test.Location"                   
## [15] "Number.of.Doses"                  "Conc.1.Type..Author."            
## [17] "Conc.1..Author."                  "Conc.1.Units..Author."           
## [19] "Effect"                           "Effect.Measurement"              
## [21] "Endpoint"                         "Response.Site"                   
## [23] "Observed.Duration..Days."         "Observed.Duration.Units..Days."  
## [25] "Author"                           "Reference.Number"                
## [27] "Title"                            "Source"                          
## [29] "Publication.Year"                 "Summary.of.Additional.Parameters"
na.omit(Neonics.data)
na.omit(Litter.data)
str(Neonics.data)
## 'data.frame':    4623 obs. of  30 variables:
##  $ CAS.Number                      : int  58842209 58842209 58842209 58842209 58842209 58842209 58842209 58842209 58842209 58842209 ...
##  $ Chemical.Name                   : Factor w/ 9 levels "(1E)-N-[(6-Chloro-3-pyridinyl)methyl]-N-ethyl-N'-methyl-2-nitro-1,1-ethenediamine",..: 9 9 9 9 9 9 9 9 9 9 ...
##  $ Chemical.Grade                  : Factor w/ 9 levels "Analytical grade",..: 9 9 9 9 9 9 9 9 9 9 ...
##  $ Chemical.Analysis.Method        : Factor w/ 5 levels "Measured","Not coded",..: 4 4 4 4 4 4 4 4 4 4 ...
##  $ Chemical.Purity                 : Factor w/ 80 levels ">=98",">=99.0",..: 69 69 50 50 50 50 50 50 50 50 ...
##  $ Species.Scientific.Name         : Factor w/ 398 levels "Acalolepta vastator",..: 69 69 248 248 248 248 248 248 248 248 ...
##  $ Species.Common.Name             : Factor w/ 303 levels "Alfalfa Leafcutter Bee",..: 74 74 142 142 142 142 142 142 142 142 ...
##  $ Species.Group                   : Factor w/ 4 levels "Insects/Spiders",..: 1 1 1 1 1 1 1 1 1 1 ...
##  $ Organism.Lifestage              : Factor w/ 20 levels "Adult","Cocoon",..: 1 1 19 19 19 1 19 1 1 19 ...
##  $ Organism.Age                    : Factor w/ 39 levels "<=24","<=48",..: 39 39 39 39 39 36 39 36 36 39 ...
##  $ Organism.Age.Units              : Factor w/ 11 levels "Day(s)","Days post-emergence",..: 9 9 4 4 4 1 4 1 1 4 ...
##  $ Exposure.Type                   : Factor w/ 24 levels "Choice","Dermal",..: 23 23 11 11 11 11 11 11 11 11 ...
##  $ Media.Type                      : Factor w/ 10 levels "Agar","Artificial soil",..: 7 7 3 3 3 3 3 3 3 3 ...
##  $ Test.Location                   : Factor w/ 4 levels "Field artificial",..: 4 4 4 4 4 4 4 4 4 4 ...
##  $ Number.of.Doses                 : Factor w/ 30 levels "' 4-5","' 4-7",..: 30 30 18 18 18 18 18 18 18 18 ...
##  $ Conc.1.Type..Author.            : Factor w/ 3 levels "Active ingredient",..: 1 1 1 1 1 1 1 1 1 1 ...
##  $ Conc.1..Author.                 : Factor w/ 1006 levels "<0.0004","<0.025",..: 639 510 813 622 442 637 500 642 814 784 ...
##  $ Conc.1.Units..Author.           : Factor w/ 148 levels "%","% v/v","% w/v",..: 132 132 91 91 91 91 91 91 91 91 ...
##  $ Effect                          : Factor w/ 19 levels "Accumulation",..: 16 16 16 16 16 16 16 16 16 16 ...
##  $ Effect.Measurement              : Factor w/ 155 levels "Abundance","Accuracy of learned task, performance",..: 87 87 87 87 87 87 87 87 87 87 ...
##  $ Endpoint                        : Factor w/ 28 levels "EC10","EC50",..: 15 15 8 8 8 8 8 8 8 8 ...
##  $ Response.Site                   : Factor w/ 19 levels "Abdomen","Brain",..: 14 14 14 14 14 14 14 14 14 14 ...
##  $ Observed.Duration..Days.        : Factor w/ 361 levels "<.0002","<.0021",..: 145 145 145 145 145 145 145 145 145 145 ...
##  $ Observed.Duration.Units..Days.  : Factor w/ 17 levels "Day(s)","Day(s) post-emergence",..: 1 1 1 1 1 1 1 1 1 1 ...
##  $ Author                          : Factor w/ 433 levels "Abbott,V.A., J.L. Nadeau, H.A. Higo, and M.L. Winston",..: 66 66 181 181 181 181 181 181 181 181 ...
##  $ Reference.Number                : int  107388 107388 103312 103312 103312 103312 103312 103312 103312 103312 ...
##  $ Title                           : Factor w/ 458 levels "A Common Pesticide Decreases Foraging Success and Survival in Honey Bees",..: 91 91 450 450 450 450 450 450 450 450 ...
##  $ Source                          : Factor w/ 456 levels "Acta Hortic.1094:451-456",..: 295 295 296 296 296 296 296 296 296 296 ...
##  $ Publication.Year                : int  1982 1982 1986 1986 1986 1986 1986 1986 1986 1986 ...
##  $ Summary.of.Additional.Parameters: Factor w/ 943 levels "Purity: \xca NC - NC | Organism Age: \xca NC - NC Not coded | Conc 1 (Author): \xca Not coded NR - NR AI lb/acr"| __truncated__,..: 572 547 122 120 124 228 119 230 233 121 ...
dim(Neonics.data)
## [1] 4623   30
length(Neonics.data)
## [1] 30
# saving new datasets write.csv(Neonics.data, file =
# './Data/Ariel_processed/Neonics.data.v2', row.names=FALSE)
# write.csv(Litter.data, file = './Data/Ariel_processed/Litter.data.v2',
# row.names=FALSE)
  1. Using the summary function on the “Effect” column, determine the most common effects that are studied. Why might these effects specifically be of interest?
summary(Neonics.data$Effect)
##     Accumulation        Avoidance         Behavior     Biochemistry 
##               12              102              360               11 
##          Cell(s)      Development        Enzyme(s) Feeding behavior 
##                9              136               62              255 
##         Genetics           Growth        Histology       Hormone(s) 
##               82               38                5                1 
##    Immunological     Intoxication       Morphology        Mortality 
##               16               12               22             1493 
##       Physiology       Population     Reproduction 
##                7             1803              197
summary(Neonics.data$Effect.Measurement)
##                                           Abundance 
##                                                1699 
##                                           Mortality 
##                                                1294 
##                                            Survival 
##                                                 133 
##                              Progeny counts/numbers 
##                                                 120 
##                                    Food consumption 
##                                                 103 
##                                           Emergence 
##                                                  98 
##                      Search/explore/forage behavior 
##                                                  96 
##                           Feeding behavior, general 
##                                                  92 
##                                  Chemical avoidance 
##                                                  65 
##                                              Weight 
##                                                  48 
##           Distance moved, change in direct movement 
##                                                  38 
##                                    Feeding behavior 
##                                                  36 
##                                     Flying behavior 
##                                                  30 
##               Accuracy of learned task, performance 
##                                                  28 
##                                           Sex ratio 
##                                                  27 
##                                           Fecundity 
##                                                  26 
##                                  Stimulus avoidance 
##                                                  26 
##                                   Righting response 
##                                                  24 
##                                            Lifespan 
##                                                  23 
##                                       Acquired task 
##                                                  22 
##                                               Hatch 
##                                                  21 
##                                  Predatory behavior 
##                                                  21 
##                                Acetylcholinesterase 
##                                                  20 
##                                                Walk 
##                                                  19 
##                                   Freezing behavior 
##                                                  18 
##                      Reproductive success (general) 
##                                                  17 
##        Slowed, Retarded, Delayed or Non-development 
##                                                  17 
##                                            Grooming 
##                                                  16 
##                                            Diameter 
##                                                  14 
##                                             Residue 
##                                                  12 
##                                   Activity, general 
##                                                  11 
##                                      Food avoidance 
##                                                  11 
##                                             Control 
##                                                   9 
##                      Developmental changes, general 
##                                                   9 
##                          Intrinsic rate of increase 
##                                                   9 
##                                    Pollen collected 
##                                                   9 
##                                                Size 
##                                                   9 
##                                            Esterase 
##                                                   8 
##                               Intoxication, general 
##                                                   8 
##                         Mortality/survival, general 
##                                                   8 
##      Population change (change in N/change in time) 
##                                                   8 
##                                         Smell/Sniff 
##                                                   8 
##                                             Biomass 
##                                                   7 
##                                       Catalase mRNA 
##                                                   7 
##                                     Generation time 
##                                                   7 
##                                            Infected 
##                                                   7 
##                                         Orientation 
##                                                   7 
##                            Population doubling time 
##                                                   7 
##                              Population growth rate 
##                                                   7 
##                                        Sealed brood 
##                                                   7 
##                                   Vitellogenin mRNA 
##                                                   7 
##                                        Ali esterase 
##                                                   6 
## Apoptosis, programmed cell death, DNA fragmentation 
##                                                   6 
##                                    Carboxylesterase 
##                                                   6 
##                                            Hemocyte 
##                                                   6 
##                                           Knockdown 
##                                                   6 
##                                           Viability 
##                                                   6 
##                                          Extinction 
##                                                   5 
##                               Net Reproductive Rate 
##                                                   5 
##                                  Polyphenol oxidase 
##                                                   5 
##                                    Prey penetration 
##                                                   5 
##                                            Pupation 
##                                                   5 
##                               Reproducing organisms 
##                                                   5 
##   Amount or percent animals infested with parasites 
##                                                   4 
##              Continual reinforcement task performed 
##                                                   4 
##                                     Defensin 1 mRNA 
##                                                   4 
##                                 Diversity, Evenness 
##                                                   4 
##              Encapsulation or Melanization Response 
##                                                   4 
##                          General biochemical effect 
##                                                   4 
##                           Glutathione S-transferase 
##                                                   4 
##                       Histological changes, general 
##                                                   4 
##                                     Life expectancy 
##                                                   4 
##                         Thioredoxin peroxidase mRNA 
##                                                   4 
##                      Vanin-like protein 1-like mRNA 
##                                                   4 
##                                   Bees wax produced 
##                                                   3 
##                         Behavioral changes, general 
##                                                   3 
##                                            Catalase 
##                                                   3 
##                                       Cell turnover 
##                                                   3 
##                                    Cytochrome P-450 
##                                                   3 
##                                        Feeding time 
##                                                   3 
##                                              Length 
##                                                   3 
##                                      Protein, total 
##                                                   3 
##                                         Respiration 
##                                                   3 
##                         Response time to a stimulus 
##                                                   3 
##                                               Stage 
##                                                   3 
##                               Time to first progeny 
##                                                   3 
##                                      Trehalase mRNA 
##                                                   3 
##                                Alkaline phosphatase 
##                                                   2 
##             Carboxylesterase clade I, member 1 mRNA 
##                                                   2 
##                                     Centractin mRNA 
##                                                   2 
##                                    Chitinase 5 mRNA 
##                                                   2 
##                           Colony maintenance (bees) 
##                                                   2 
##                                           COX2 mRNA 
##                                                   2 
##                               Endoplasmin-like mRNA 
##                                                   2 
##                                   Gamete production 
##                                                   2 
##                        Glucose dehydrogenase 2 mRNA 
##                                                   2 
##                       Glucosinolate sulphatase mRNA 
##                                                   2 
##                  Glutathione peroxidase-like 1 mRNA 
##                                                   2 
##                  Glutathione peroxidase-like 2 mRNA 
##                                                   2 
##                                             (Other) 
##                                                  77

Answer: The main effects in this dataset are mortality, feeding behavior, population, behavior and mortality. These are all important aspects to study for species survial and better understanding population estimates.

  1. Using the summary function, determine the six most commonly studied species in the dataset (common name). What do these species have in common, and why might they be of interest over other insects? Feel free to do a brief internet search for more information if needed.
summary(Neonics.data$Species.Common.Name)
##                          Honey Bee                     Parasitic Wasp 
##                                667                                285 
##              Buff Tailed Bumblebee                Carniolan Honey Bee 
##                                183                                152 
##                         Bumble Bee                   Italian Honeybee 
##                                140                                113 
##                    Japanese Beetle                  Asian Lady Beetle 
##                                 94                                 76 
##                     Euonymus Scale                           Wireworm 
##                                 75                                 69 
##                  European Dark Bee                  Minute Pirate Bug 
##                                 66                                 62 
##               Asian Citrus Psyllid                      Parastic Wasp 
##                                 60                                 58 
##             Colorado Potato Beetle                    Parasitoid Wasp 
##                                 57                                 51 
##                Erythrina Gall Wasp                       Beetle Order 
##                                 49                                 47 
##        Snout Beetle Family, Weevil           Sevenspotted Lady Beetle 
##                                 47                                 46 
##                     True Bug Order              Buff-tailed Bumblebee 
##                                 45                                 39 
##                       Aphid Family                     Cabbage Looper 
##                                 38                                 38 
##               Sweetpotato Whitefly                      Braconid Wasp 
##                                 37                                 33 
##                       Cotton Aphid                     Predatory Mite 
##                                 33                                 33 
##             Ladybird Beetle Family                         Parasitoid 
##                                 30                                 30 
##                      Scarab Beetle                      Spring Tiphia 
##                                 29                                 29 
##                        Thrip Order               Ground Beetle Family 
##                                 29                                 27 
##                 Rove Beetle Family                      Tobacco Aphid 
##                                 27                                 27 
##                       Chalcid Wasp             Convergent Lady Beetle 
##                                 25                                 25 
##                      Stingless Bee                  Spider/Mite Class 
##                                 25                                 24 
##                Tobacco Flea Beetle                   Citrus Leafminer 
##                                 24                                 23 
##                    Ladybird Beetle                          Mason Bee 
##                                 23                                 22 
##                           Mosquito                      Argentine Ant 
##                                 22                                 21 
##                             Beetle         Flatheaded Appletree Borer 
##                                 21                                 20 
##               Horned Oak Gall Wasp                 Leaf Beetle Family 
##                                 20                                 20 
##                  Potato Leafhopper         Tooth-necked Fungus Beetle 
##                                 20                                 20 
##                       Codling Moth          Black-spotted Lady Beetle 
##                                 19                                 18 
##                       Calico Scale                Fairyfly Parasitoid 
##                                 18                                 18 
##                        Lady Beetle             Minute Parasitic Wasps 
##                                 18                                 18 
##                          Mirid Bug                   Mulberry Pyralid 
##                                 18                                 18 
##                           Silkworm                     Vedalia Beetle 
##                                 18                                 18 
##              Araneoid Spider Order                          Bee Order 
##                                 17                                 17 
##                     Egg Parasitoid                       Insect Class 
##                                 17                                 17 
##           Moth And Butterfly Order       Oystershell Scale Parasitoid 
##                                 17                                 17 
## Hemlock Woolly Adelgid Lady Beetle              Hemlock Wooly Adelgid 
##                                 16                                 16 
##                               Mite                        Onion Thrip 
##                                 16                                 16 
##              Western Flower Thrips                       Corn Earworm 
##                                 15                                 14 
##                  Green Peach Aphid                          House Fly 
##                                 14                                 14 
##                          Ox Beetle                 Red Scale Parasite 
##                                 14                                 14 
##                 Spined Soldier Bug              Armoured Scale Family 
##                                 14                                 13 
##                   Diamondback Moth                      Eulophid Wasp 
##                                 13                                 13 
##                  Monarch Butterfly                      Predatory Bug 
##                                 13                                 13 
##              Yellow Fever Mosquito                Braconid Parasitoid 
##                                 13                                 12 
##                       Common Thrip       Eastern Subterranean Termite 
##                                 12                                 12 
##                             Jassid                         Mite Order 
##                                 12                                 12 
##                          Pea Aphid                   Pond Wolf Spider 
##                                 12                                 12 
##           Spotless Ladybird Beetle             Glasshouse Potato Wasp 
##                                 11                                 10 
##                           Lacewing            Southern House Mosquito 
##                                 10                                 10 
##            Two Spotted Lady Beetle                         Ant Family 
##                                 10                                  9 
##                       Apple Maggot                            (Other) 
##                                  9                                670

Answer: The most common are Honey Bee, Parasitic Wasp, Buff Tailed Bumblebee, Carniolan Honey Bee, Bumble Bee, and Italian Honeybee. Most of the top insects sudied are bees which are pollnators and a keystone species for our food production.

  1. Concentrations are always a numeric value. What is the class of Conc.1..Author. in the dataset, and why is it not numeric?
class(Neonics.data$Conc.1..Author.)
## [1] "factor"

Answer:The class(Neonics.data$Conc.1..Author.) shows up as “factor” because it is not a numerical data set with continuous or descrete values. This column is a categorical dataset.

Explore your data graphically (Neonics)

  1. Using geom_freqpoly, generate a plot of the number of studies conducted by publication year.
ggplot(Neonics.data) + geom_freqpoly(aes(x = Publication.Year), bins = 15)

ggplot(Neonics.data) + geom_freqpoly(aes(x = Publication.Year), bins = 25)

  1. Reproduce the same graph but now add a color aesthetic so that different Test.Location are displayed as different colors.
ggplot(Neonics.data) + geom_freqpoly(aes(x = Publication.Year), bins = 15, color = "red")

ggplot(Neonics.data) + geom_freqpoly(aes(x = Publication.Year, color = Test.Location),
    bins = 15)

Interpret this graph. What are the most common test locations, and do they differ over time?

Answer: The most common testing locations are the labs and natural field. The lab testing only supparsed natral field around 2009 and beacame the most common test location.

  1. Create a bar graph of Endpoint counts. What are the two most common end points, and how are they defined? Consult the ECOTOX_CodeAppendix for more information.
ggplot(Neonics.data, aes(x = Endpoint)) + geom_bar()

# label_parsed(Endpoint, multi_line = TRUE) did not work try to space text on X
# axis

Answer:The two most common end points are LOEC and NEOL.

Explore your data (Litter)

  1. Determine the class of collectDate. Is it a date? If not, change to a date and confirm the new class of the variable. Using the unique function, determine which dates litter was sampled in August 2018.
# help('as.Date') Litter.data
# <-read.csv('Data/Raw/NEON_NIWO_Litter_massdata_2018-08_raw.csv',
# stringsAsFactors = TRUE)
class(Litter.data$collectDate)  # checking current class
## [1] "factor"
Litter.data$collectDate <- c(ymd(Litter.data$collectDate))  #Changing to date format
class(Litter.data$collectDate)  #checking the changed class
## [1] "Date"
unique(Litter.data$collectDate)
## [1] "2018-08-02" "2018-08-30"
# Litter.data.datetime <- as.Date.factor(Litter.data$collectDate, format=
# '%Y/%m/%d') - Do not use na.omit(Litter.data.datetime)
# format(Litter.data$collectDate, format= '%Y/%m/%d') do not use
# class(Litter.data.datetime$collectDate)
  1. Using the unique function, determine how many plots were sampled at Niwot Ridge. How is the information obtained from unique different from that obtained from summary?
# help('unique') help(summary)
unique(Litter.data$plotID)
##  [1] NIWO_061 NIWO_064 NIWO_067 NIWO_040 NIWO_041 NIWO_063 NIWO_047 NIWO_051
##  [9] NIWO_058 NIWO_046 NIWO_062 NIWO_057
## 12 Levels: NIWO_040 NIWO_041 NIWO_046 NIWO_047 NIWO_051 NIWO_057 ... NIWO_067

Answer:The uniuqe function returns a vector, data frame or array with dupliance elements/rows removed. The summary is a generic function which produces summaries of the various functions.

  1. Create a bar graph of functionalGroup counts. This shows you what type of litter is collected at the Niwot Ridge sites. Notice that litter types are fairly equally distributed across the Niwot Ridge sites.
ggplot(Litter.data, aes(x = functionalGroup)) + geom_bar()

  1. Using geom_boxplot and geom_violin, create a boxplot and a violin plot of dryMass by functionalGroup.
ggplot(Litter.data) + geom_boxplot(aes(x = dryMass, y = functionalGroup))

ggplot(Litter.data) + geom_violin(aes(x = dryMass, y = functionalGroup), draw_quantiles = c(0.25,
    0.5, 0.75))
## Warning in regularize.values(x, y, ties, missing(ties), na.rm = na.rm):
## collapsing to unique 'x' values

## Warning in regularize.values(x, y, ties, missing(ties), na.rm = na.rm):
## collapsing to unique 'x' values

## Warning in regularize.values(x, y, ties, missing(ties), na.rm = na.rm):
## collapsing to unique 'x' values

Why is the boxplot a more effective visualization option than the violin plot in this case?

Answer:The boxplot allows you to see the were the majority of the groupings are for the functional groups by drymass but also the outliners. The violin plots which display density distribution are not as effective.

What type(s) of litter tend to have the highest biomass at these sites?

Answer:Needles have the highest biopass at these sights.